Handling cell reselections and state transitions for high-speed downlink packet access

ABSTRACT

A wireless transmit receive unit (WTRU) is configured to operate in an high speed data packet access (HSDPA) mode in a cell and/or state and to clear HSDPA resources when moving out of the cell and/or state. The WTRU is configured to clear HSDPA resources when conditions to perform high speed downlink shared channel reception are not met.

CROSS REFERENCE TO RELATED APPLICATIONS

This continuation application claims the benefit of U.S. applicationSer. No. 14/618,627, filed Feb. 10, 2015, which claims the benefit ofU.S. application Ser. No. 13/349,898, filed Jan. 13, 2012, now U.S. Pat.No. 8,982,837, which claims the benefit of U.S. application Ser. No.12/112,103, filed Apr. 30, 2008, now U.S. Pat. No. 8,184,591, whichclaims the benefit of U.S. Provisional Application No. 60/915,048, filedApr. 30, 2007, 60/944,661, filed Jun. 18, 2007, 60/944,540, filed Jun.18, 2007, and 60/955,578, filed Aug. 13, 2007, the contents of eachbeing incorporated by reference as if fully set forth therein.

FIELD OF INVENTION

The present application is related to wireless communication.

BACKGROUND

Wireless transmit receive units (WTRUs) in a UMTS Terrestrial RadioAccess Network (UTRAN) can be in either of two modes: Idle or Connected.Based on WTRU mobility and activity while in connected mode, the UTRANcan direct the WTRU to transition between a number of radio resourcecontrol (RRC) sub-states: Cell_PCH, URA_PCH, Cell_DCH and Cell_FACH. TheCell-PCH and URA_PCH states are used to trigger cell updates on a pagingchannel (PCH) for a mobile WTRU. The Cell_DCH state is characterized bydedicated channels (DCHs) in both the uplink and the downlink. On theWTRU side, this corresponds to continuous transmission and reception andcan be demanding on user power requirements. The Cell_FACH state ischaracterized by a forward access channel (FACH) and does not usededicated channels, thus allowing better power consumption, at theexpense of a lower uplink and downlink throughput.

Recent work by the standardization bodies has identified the possibilityof using high speed downlink packet access (HSDPA) in Cell_FACH andCell_PCH/URA_PCH. HSDPA is a feature that was introduced in Release 5 ofthe 3rd Generation Partnership Project (3GPP) specifications to operatein Cell_DCH. HSDPA tries to make better use of the downlink sharedcapacity by using three key concepts: Adaptive Modulation and Coding(AMC), retransmissions using a Hybrid-ARQ (HARQ) scheme, and Node Bscheduling, all operating at a very fast rate.

The following HSDPA characteristics are relevant:

-   -   a. Every WTRU having a HSDPA connection is assigned a high speed        downlink scheduling channel (HS-DSCH) Radio Network Temporary        Identifier (H-RNTI). This identifier is unique within a cell and        assigned by the serving Radio Network Controller (RNC).    -   b. A WTRU is attached to a single serving cell (Node B).    -   c. The WTRU has to receive indication of the physical channel        resources to use (HS-PDSCH info), as well as how to set up the        HARQ processes and the HARQ memory.

In 3GPP Release 6, HSDPA was only supported in Cell_DCH. Therefore, whenmoving out of Cell_DCH state, all HSDPA resources had to be cleared.However, with the introduction of enhanced Cell_FACH the WTRU may movefrom Cell_DCH to any other state and still support HS-DSCH reception,which may not require the WTRU to clear all HSDPA resources. Therefore,an additional condition was added to the variable HS_DSCH_RECEPTIONassociated with HS-DSCH reception in Cell_DCH. The HSDPA resources areonly cleared when the requirements to perform HS-DSCH reception are notmet and the WTRU is in Cell_DCH.

It is assumed that if a WTRU supports HSDPA in Release 7, it alsosupports HSDPA in Cell_FACH and in Cell_PCH/URA_PCH. HS-DSCH receptionin Cell_FACH can be configured without HS-DSCH reception in Cell_PCH andURA_PCH. HS-DSCH reception in Cell_PCH and URA_PCH without the supportof HS-DSCH reception in Cell_FACH is not supported. The WTRU support forthese features is signaled by the WTRU to the network.

The network signals its support for enhanced Cell_FACH via the SystemInformation Block (SIB5/5bis) to the WTRU. Two new information elements(IEs) have been introduced:

-   -   a. “HS-DSCH common system information”—indicating the HSDPA        reception is supported for Cell_FACH state; and    -   b. “HS-DSCH paging system information”—indicating that HSDPA is        supported for Cell_PCH/URA_PCH state.        To indicate whether HS-DSCH reception is ongoing in Cell_FACH,        two new Boolean variables have been introduced, which are used        as flags by the WTRU radio resource control (RRC) controller:    -   a. HS_DSCH_RECEPTION_Cell_FACH_STATE: If TRUE indicates that        HS_DSCH reception in Cell_FACH reception is ongoing; and    -   b. HS_DSCH_RECEPTION_OF_CCCH_OF_ENABLED: If TRUE indicates that        HS-DSCH reception is enabled for CCCH. This variable is set to        TRUE when the WTRU is using a common H-RNTI to receive HSDPA        traffic, and is set to FALSE when the WTRU is not.        However, no new variable has been defined for HS-DSCH reception        indication in Cell_PCH or URA_PCH states. When in Cell_PCH or        URA_PCH, and if the IE “HS-DSCH paging system information” is        broadcasted, the WTRU sets up HSDPA reception.

Scenarios can occur where the WTRU transitions from Cell_DCH to a statethat does not support HSDPA. For instance, the WTRU could transitionfrom Cell_DCH to Cell_FACH in a cell that does not support the EnhancedCell_FACH feature, or the WTRU could transition from Cell_DCH toCell_PCH in a cell that does not support HS-DSCH reception in Cell_PCH.In such scenarios the HSDPA resources are not cleared and the WTRU willcontinue to perform HS-DSCH reception procedures. This behavior isundesirable since the WTRU will waste resources and battery whileattempting to receive on this channel. In addition, failure to clearHSDPA resources (i.e. clear IEs, release HARQ resources, performingenhanced high speed medium access channel (MAC-ehs) reset) is likely tocause problems when the WTRU resumes HS-DSCH reception in another state.

Similar problems occur in some scenarios of cell reselection. Forinstance, the WTRU may reselect from a cell that supports HS-DSCH inCELL to a cell that does not support the Enhanced Cell_FACH feature andthe HSDPA resources are not cleared.

SUMMARY

A method and apparatus for cell reselection in 3GPP wirelesscommunication is implemented by a wireless transmit/receive unit (WTRU)that supports HS-DSCH reception. When in cell transition or statetransition, the WTRU checks whether there is an ongoing HS-DSCHreception, and if the new cell or state cannot support HS-DSCH, then theHSDPA resources being used for the ongoing HS-DSCH reception arereleased. The WTRU performs this method using radio resource control(RRC) processing, which monitors various events and conditions to makethe determination whether to release HSDPA resources.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1 shows a block diagram of a wireless transmit/receive unit (WTRU)and a various Node B candidates for cell/state reselection;

FIG. 2 is an example functional block diagram of a WTRU and the Node Bof FIG. 1; and

FIG. 3 is a flow diagram of a method for implementing an RRC variableHS_DSCH_RECEPTION_GENERAL, which tracks HS-DSCH reception for allstates.

DETAILED DESCRIPTION

When referred to hereafter, the terminology “wireless transmit/receiveunit (WTRU)” includes but is not limited to a user equipment (UE), amobile station, a fixed or mobile subscriber unit, a pager, a cellulartelephone, a personal digital assistant (PDA), a computer, or any othertype of user device capable of operating in a wireless environment. Whenreferred to hereafter, the terminology “base station” includes but isnot limited to a Node-B, a long term evolution enhanced NodeB (eNB), asite controller, an access point (AP), or any other type of interfacingdevice capable of operating in a wireless environment.

The terms “clearing and releasing of HSDPA resources” and “stopping ofHS-DSCH reception procedures” are herein used interchangeably.

When referred to hereafter, the terminology “3GPP Release 7 (R7)”,includes but is not limited to a WTRU or Node B that supports HS-DSCH inCELL_FACH and/or CELL/URA_PCH and “3GPP Release 6 (R6)” includes but isnot limited to a WTRU or Node B that supports HS-DSCH in CELL_FACHand/or CELL/URA_PCH.

HS-DSCH in CELL_FACH also includes HS-DSCH reception in idle mode forthe reception of RRC connection procedures.

FIG. 1 shows an example wireless communication system 100 of cells 20,30 and 40, with NodeBs 120, 130 and 140 respectively. A mobile WTRU 110is in communication with a serving Node B 120, and NodeBs 130 and 140are candidates for cell reselection. It should be noted that, althoughan example configuration of WTRU 110 and Node B 120 is depicted in FIG.1, any combination of wireless and wired devices may be included in thewireless communication system 100.

FIG. 2 is an example functional block diagram 200 of a WTRU 110 and theNode B 120 of the wireless communication system 100 of FIG. 1. As shownin FIG. 2, the WTRU 110 is in communication with the Node B 120.

In addition to the components that may be found in a typical WTRU, theWTRU 110 includes a processor 115, a receiver 116, a transmitter 117,and an antenna 118. The receiver 116 and the transmitter 117 are incommunication with the processor 115. The antenna 118 is incommunication with both the receiver 116 and the transmitter 117 tofacilitate the transmission and reception of wireless data. Theprocessor 115 of the WTRU 110 is configured to handle cell reselectionsand state transitions to and from an enhanced Cell_FACH state.

In addition to the components that may be found in a typical Node B, theNode B 120 includes a processor 125, a receiver 126, a transmitter 127,and an antenna 128. The receiver 126 and the transmitter 127 are incommunication with the processor 125. The antenna 128 is incommunication with both the receiver 126 and the transmitter 127 tofacilitate the transmission and reception of wireless data. Theprocessor 125 of the Node B 120 is configured to support enhancedCell_FACH state.

Embodiments are disclosed that deal with state/cell transitions from astate or cell where HS-DSCH reception is possible, to a state or cellwhere HS-DSCH reception is not possible.

Cell Reselection

In this case, the WTRU is not waiting for a CELL UPDATE CONFIRM from thenetwork. That is, the WTRU is in state Cell_FACH, and makes a cellre-selection. The cell reselection process can be considered a 2-stepprocess. The first step sets up the HSDPA communication in the new cell,if this new cell is 3GPP R7 capable. The second step deals with theclearing of information from the old cell. This second step shouldconsider all possible transitions that may occur: 3GPP R7 cell to R7cell, 3GPP R7 cell to R6 Cell, 3GPP R6 cell to R7 cell, and 3GPP R6 cellto R6 cell. Any time a cell reselection to a 3GPP R6 cell occurs, anyHSDPA configuration should be removed (a complete HSDPA reset). On theother hand, if a transition is to a 3GPP R7 capable cell, only a MAC-hsreset would be needed. Further, the first step should specifically checkthat a cell reselection is occurring. The second clause is specific tocell reselection. If cell is not 3GPP R7 capable, then a complete HSDPAreset is performed (stop monitoring HS-SCCH and HS-PDSCH, mac-hs reset,release of HARQ resources). This reset can be implemented by specifyingthe individual actions, or by using the variables(HS_DSCH_RECEPTION_Cell_FACH_STATE & HS_DSCH_RECEPTION_OF_CCCH) andperforming required actions.

State Transitions

Transitions from Cell_DCH

Transitions from Cell_DCH state can be requested through a number of RRCmessages, such as:

-   -   RADIO BEARER SETUP    -   RADIO BEARER RECONFIGURATION    -   RADIO BEARER RELEASE    -   TRANSPORT CHANNEL RECONFIGURATION    -   PHYSICAL CHANNEL RECONFIGURATION        When performing procedures related to these messages, a WTRU may        be asked to transition from Cell_DCH state to Cell_FACH,        Cell_PCH, and URA_PCH. Depending on the cell capabilities, the        states being entered can support HSDPA or not (3GPP R7 cells        support HSDPA in Cell_FACH, Cell_PCH, URA_PCH, while 3GPP R6        cells do not). As a result, any transition to a non-HSDPA state        from a HSDPA state should result in a complete HSDPA reset (stop        monitoring HS-SCCH & HS-PDSCH, mac-hs reset, release of HARQ        resources). However, for transitions to a state that supports        HSDPA no reset is needed.

Currently, the resetting is performed when evaluating the variableHS_DSCH_RECEPTION. If this variable was “TRUE” and becomes “FALSE” afterthe evaluation, then a complete HSDPA reset is performed provided thatthe UE is in state Cell_DCH.

In accordance with this embodiment, the WTRU 110 performs a reset (i.e.,release of HSDPA resources) in cases where the WTRU 110 moves to statesthat do not support HSDPA. This can be determined from the presence orabsence of the IE “Downlink HS-PDSCH system information” or “HS-DSCHcommon system information” in System Information Block 5 and/or thepresence or absence of the IE “Downlink HS-PDSCH system information forconnected mode” in System Information Block 6.

Transitions from Cell_FACH

State transitions out of Enhanced Cell_FACH state have the same issue astransitions out of Cell_DCH. That is, any time a transition is to astate that does not support HSDPA, a complete HSDPA reset should berequired. The resetting is performed when evaluating the variableHS_DSCH_RECEPTION_Cell_FACH_STATE. If this variable is “TRUE” andbecomes “FALSE” after the evaluation, then a complete HSDPA reset isperformed provided that the WTRU is in state Cell_FACH and the variableHS_DSCH_RECEPTION_OF_CCCH is “FALSE”. This reset is also performed incases where the WTRU 110 transitions to states that do not supportHSDPA.

An explicit check of the variable is made when the WTRU 110 receives anyRRC message that causes a transition from Cell_FACH to Cell_PCH orURA_PCH. This includes commands such as:

-   -   RADIO BEARER SETUP    -   RADIO BEARER RECONFIGURATION    -   RADIO BEARER RELEASE    -   TRANSPORT CHANNEL RECONFIGURATION    -   PHYSICAL CHANNEL RECONFIGURATION    -   CELL UPDATE CONFIRM        To determine whether or not the state to which the WTRU 110        transitioned supports HSDPA, the WTRU 110 can use the presence        or absence of the IE “Downlink HS-PDSCH system information” or        “HS-DSCH common system information” in System Information Block        5 and/or the presence or absence of the IE “Downlink HS-PDSCH        system information for connected mode” in System Information        Block 6.

General Overview

The WTRU 110 clears HSDPA resources and stops HS-DSCH receptionprocedures when the WTRU 110 moves from a state or cell in which it isperforming HS-DSCH reception (e.g., a 3GPP Release 7 capable state orcell) to a state or cell in which it no longer supports HS-DSCHreception (e.g., a 3GPP Release 6 capable state or cell).

When the WTRU 110 attempts to establish a HSDPA connection as a resultof a state transition, and/or cell change (cell re-selection), and theconditions required to perform HS-DSCH reception are not met, the WTRU110 clears the HSDPA resources. The WTRU 110 can always clear the HSDPAresources or it clears HSDPA resources only if the previous state orcell had an ongoing HS-DSCH reception procedure.

The actions related to clearing of HSDPA resources and stopping HS-DSCHreception procedures include, but are not limited to the following:

-   -   stopping any HS-SCCH reception/monitoring procedures;    -   stopping any HS-DSCH reception/monitoring procedures;    -   clearing the variable H_RNTI and remove any stored H-RNTI;    -   resetting the MAC-hs/ehs entity; and    -   releasing all HARQ resources.

If more resources are added to the HS-DSCH connection procedures, theWTRU 110 may also clear those resources. For example, the WTRU 110 mayalso need to clear the common H-RNTI values or any IEs stored (e.g.,HARQ info).

Checking if HS-DSCH Reception is Ongoing

In some scenarios, the WTRU 110 needs to check if there is an ongoingHS-DSCH reception procedure (i.e., prior to state transition,configuration, cell reselection, and the like). In order to check ifthere is an ongoing HS-DSCH reception procedure, one or a combination ofthe following procedures may be used:

A new Boolean HS-DSCH reception variable HS_DSCH_RECEPTION_GENERAL maybe defined by the processor 115 used for the radio resource control(RRC) processing, and used to act as a flag to indicate whether HS-DSCHreception is ongoing in any of the four states Cell_FACH, Cell_DCH,Cell_PCH, URA_PCH. For example, this may be implemented by a RRCcontroller function in the processor 115. The variable is set to TRUEwhen HS-DSCH reception is supported and started in any state, and it isset to FALSE when stopping HS-DSCH reception and/or when HS-DSCHreception is not supported.

A new state variable HS_DSCH_RECEPTION_PCH_STATE for Cell_PCH/URA_PCHstate may be defined by the processor 115 for RRC processing (e.g., in aRRC controller function of the processor 115) and used to check ifHS-DSCH reception is ongoing in the Cell_PCH/URA_PCH state.

The existing HS_DSCH reception variables (HS_DSCH_RECEPTION,HS_DSCH_RECEPTION_Cell_FACH_STATE, HS_DSCH_RECEPTION_OF_CCCH_(—)ENABLED, or HS_DSCH_RECEPTION_PCH_STATE) may also be used if applicable.If any of these variables is set to TRUE, it means that a HS-DSCHreception procedure is ongoing. For example, if the WTRU 110 is inCell_FACH and wants to know if HS-DSCH reception is ongoing, in additionto the state variable (i.e. HS_DSCH_RECEPTION_Cell_FACH_STATE), the WTRU110 also checks all other HS-DSCH reception variables.

A MAC-ehs state indication may be used to denote ongoing HSDPAreception. This could include a newly defined state indicator, specialreserved values for MAC-ehs state variables (next_expected_TSN, T1), orwhether any HARQ resources have been configured. Only the last option isincluded in the embodiments using a MAC-ehs state indication. For properoperation of the state indication, the HARQ resources should be clearedwhen not using HSDPA.

Conditions for Releasing HS-DSCH Resources

The proper behavior of the WTRU 110 may be defined according to one or acombination of the following RRC procedures in the processor 115. TheWTRU 110 first checks for the following HS-DSCH reception criteria,which is monitoring whether any of the following events have occurred:

-   -   a. State transitions due to RRC reconfigurations, RRC setup, RRC        release messages:        -   i. Cell_DCH to Cell_FACH, Cell_PCH, or URA_PCH;        -   ii. Cell_FACH to Cell_PCH, or URA_PCH;    -   b. Cell Update and cell reselection cases:        -   i. Radio Link failure (from Cell_DCH to Cell_FACH);        -   ii. Cell reselection from Cell_FACH to Cell_FACH;        -   iii. Cell reselection from Cell_PCH to Cell_FACH;    -   c. Cell reselection in idle mode while waiting for RRC        CONNECTION SETUP message (i.e. resending RRC CONNECTION REQUEST        due to cell reselection):        -   i. Cell reselection in URA_PCH (i.e. when reading the            SIB5/5bis and SIB6/6bis);    -   d. Timer T302 expiry of cell reselection.        Alternatively, this check may be done in other procedures and        cases where the WTRU 110 check for HS-DSCH reception is        supported (i.e. reading of SIB5/5bis, SIB 6/6bis actions).

The WTRU 110 further checks the following conditions to ascertainwhether HS-DSCH reception is supported in the new state:

Following a state transition to Cell_FACH state, the WTRU 110 checks:

-   -   for TDD; or    -   for FDD, if the WTRU does not support HS-DSCH reception; or    -   if the IE “HS-DSCH common system information” is not included in        System Information Block type 5 or System Information Block type        5bis.        Following a state transition to Cell_PCH or URA_PCH, the WTRU        110 checks:    -   for TDD; or    -   for FDD, if the WTRU does not support HS-DSCH reception; or    -   if the IE “HS-DSCH paging system information” is not included.        When one of these above conditions is TRUE, the WTRU 110 takes        the action of clearing the HSDPA resources. As a first        variation, the HSDPA resources may always be cleared upon        satisfying any of the above conditions. As a second variation,        the HSDPA resources are cleared upon any of the above conditions        and if HS-DSCH reception was previously ongoing in any of the        other states prior to the start of the RRC procedure.

In order to check if the WTRU 110 supports HS-DSCH reception inCELL_FACH and/or CELL_PCH/URA_PCH, an additional WTRU capability may beadded, instead of just checking whether the WTRU 110 supports HS-DSCHreception. For example, the following additional WTRU capabilities maybe added to the RRC procedure:

-   -   a. HS-DSCH support in Cell_FACH (i.e., only for Cell_FACH);    -   b. HS-DSCH support in Cell_PCH or URA_PCH (which also implies        HS-DSCH support in Cell_FACH).        If such capabilities are added, the WTRU 110 would perform these        checks as part of the steps described above.

Actions Related to Clearing HSDPA Resources

To perform the actions related to clearing HSDPA resources, the WTRUprocessor 115 executes one or a combination of the following:

-   -   a. Clearing HSDPA resources when the conditions to start HS-DSCH        reception are not met.    -   b. When HS-DSCH reception criteria are not met AND if HS-DSCH        reception is ongoing for the current state of the WTRU 110 (i.e.        HS_DSCH_RECEPTION_GENERAL set to TRUE), then the variable        HS_DSCH_RECEPTION_GENERAL is set to FALSE and HSDPA resources        are cleared.    -   c. Evaluate and perform the actions corresponding to the        existing HS-DSCH reception variables or any newly introduced        variable (i.e. for Cell_PCH/URA_PCH). The variables to be        evaluated can be one or a combination of the following:        -   i. HS_DSCH_RECEPTION variable;        -   ii. HS_DSCH_RECEPTION_Cell_FACH_STATE variable;        -   iii. HS_DSCH_RECEPTION_OF_CCCH_ENABLED variable; or        -   iv. A variable for Cell_PCH/URA_PCH    -    If the conditions to set one of these variables to TRUE are not        met, the WTRU 110 may use one of the procedures described herein        to check if there is an ongoing HS-DSCH reception. If there is        an ongoing HS-DSCH connection, then the WTRU may release all        HSDPA resources. Alternatively, the WTRU may release all HSDPA        resources whenever the variable which is being evaluated is set        to FALSE.    -   d. The evaluation and actions corresponding to variables of        HS-DSCH reception in Cell_FACH and Cell_PCH/URA_PCH are only        done when the conditions to perform HS-DSCH reception are met.        As part of this option, these variables and/or actions are        executed even when the conditions are not met in the procedures        described above.    -   e. In addition to one of the changes performed above, the        actions related to the HS_DSCH_RECEPTION variable for Cell_DCH        can be modified to clear the resources if the conditions to        perform HS-DSCH reception in Cell_FACH and Cell_URA/Cell_PCH are        not met. This will only solve one of the problems identified        (moving out of Cell_DCH to any other state).

The above methods described for checking if HS-DSCH reception isongoing, performing RRC actions, and performing the actions related toHSDPA clearing may be combined together to solve the problemsidentified.

HSDPA Variable Applicable to all States

The Boolean variable HS_DSCH_RECEPTION_GENERAL is set to TRUE dependingon whether the WTRU 110 has been configured to start HS-DSCH reception.When the WTRU 110 first powers up, this variable is set to FALSE. Aspart of the idle mode procedure, the WTRU 110 then sends a RRCConnection request message. When the message is sent, the WTRU 110processes the received downlink to confirm that the network supportsHS-DSCH (e.g., by checking flags in the SIB5/5bis). If HS-DSCH issupported, the WTRU 110 performs actions associated withHS_DSCH_RECEPTION_OF_CCCH variable: if TRUE, then it means that HS-DSCHreception is ongoing. Accordingly, the variableHS_DSCH_RECEPTION_GENERAL is also set to TRUE. TheHS_DSCH_RECEPTION_GENERAL is set to TRUE in any of the four states, whenthe conditions to start HS-DSCH reception are met. Below are describedinstances when the variable is set to TRUE. The variableHS_DSCH_RECEPTION_GENERAL is defined and controlled by the WTRUprocessor 115, the variable acting as a flag to indicate whether HS-DSCHreception is ongoing in any of the four states Cell_DCH, Cell_FACH,Cell_PCH and URA_PCH. The WTRU 110 relies on this variable to check ifthere is an ongoing HS-DSCH reception procedure. If the variableHS_DSCH_RECEPTION_GENERAL is set to TRUE, it implies that there is anongoing HS-DSCH reception procedure. If the WTRU 110 cannot supportHS-DSCH reception in the new state/cell upon state/cell transition, theWTRU 110 clears all HSDPA resources and sets the variableHS_DSCH_RECEPTION_GENERAL to FALSE. In order to ensure that thisvariable is properly set at all times, this variable is set based on theactions associated with HS-DSCH reception in all the states.

The HS_DSCH_RECEPTION_GENERAL variable is set to TRUE when any of therequirements to setup HS-DSCH reception in the appropriate states aremet and the HS-DSCH reception is started. This can happen in any of thefollowing cases:

-   -   a. HS_DSCH_RECEPTION is set to TRUE in Cell_DCH;    -   b. HS_DSCH_RECEPTION_Cell_FACH_STATE is set to TRUE in        Cell_FACH;    -   c. HS_DSCH_RECEPTION_OF_CCCH_ENABLED is set to TRUE in Cell_FACH        and idle when the WTRU has a common H-RNTI;    -   d. Actions related to HS-DSCH reception in Cell_PCH/URA_PCH are        executed and the conditions are met; and    -   e. the IE “HS-DSCH common system information” is included in        System Information Block type 5 or System Information Block type        5bis (e.g., during Radio Bearer Setup, Radio Bearer        Reconfiguration, Radio Bearer Release, Transport channel        Reconfiguration, or PHY channel reconfiguration.        When the above requirements associated with the HS-DSCH        reception variables for the different states are not met and any        of the above mentioned HS-DSCH reception variables are set to        FALSE, the HS_DSCH_RECEPTION_GENERAL should also be set to        FALSE.

Additionally, if the existing variables are modified or an additionalvariable is added for the states Cell_PCH and URA_PCH, the setting ofHS_DSCH_RECEPTION_GENERAL may be correlated to the setting of themodified or new variables, as described above. Whenever HS-DSCHreception is properly setup, the variable HS_DSCH_RECEPTION_GENERAL isset to TRUE. Whenever HS-DSCH reception is stopped and/or not supportedin the state/cell WTRU is operating on, it should be set to FALSE.

Actions Related to Variable HS_DSCH_RECEPTION_GENERAL

When the WTRU 110 is performing initiation procedures related toacquiring system information to setup in the new cell or the new state,the WTRU 110 checks if HSDPA is supported. When HS-DSCH reception is notsupported, the WTRU 110 performs secondary common control physicalchannel (S-CCPCH) selection, and the WTRU 110 may clear HS-DSCHresources if an HS-DSCH reception procedure is ongoing, and the WTRU 110sets the HS_DSCH_RECEPTION_GENERAL variable to FALSE.

The WTRU 110 can check if HS-DSCH reception is ongoing by checking thevariable HS_DSCH_RECEPTION_GENERAL. If this variable is set to TRUE, andthe WTRU 110 does not support HSDPA in its current state/cell (i.e., thenew state/cell upon transition), the WTRU sets this variable to FALSE,and performs the following steps related to clearing HSDPA resources:

-   -   a. stop any HS-SCCH reception procedures;    -   b. stop any HS-DSCH reception procedures;    -   c. clear the variable H_RNTI and remove any stored H-RNTI;    -   d. reset the MAC-hs entity;    -   e. release/reset all HARQ resources;    -   f. clear any stored IEs HARQ information.        For TDD and for FDD, whenever the variable        HS_DSCH_RECEPTION_GENERAL is set to FALSE, the WTRU 110:    -   does not perform a HS_SCCH reception procedure;    -   does not perform a HS_DSCH reception procedure.        It should be noted that if any criteria changes for checking for        support of HS-DSCH reception for the cell and WTRU, the above        described procedures associated with WTRU 110 actions to clear        HSDPA resources according to the variable        HS_DSCH_RECEPTION_GENERAL may still be applied.

For the above scenarios under this embodiment, the WTRU 110 ensures thatthe HS_DSCH_RECEPTION_GENERAL variable is set to FALSE. Optionally, theWTRU 110 can also ensure that all other HS-DSCH variables are also setto FALSE. In addition, the WTRU 110 releases any HSDPA resources andstops HS-DSCH reception procedures, if any HS-DSCH reception is ongoing.The HS_DSCH_RECEPTION_GENERAL variable is also set to FALSE when theWTRU is entering UTRA RRC connected mode when not otherwise stated inthe RRC procedure, and when the WTRU is leaving UTRA RRC connected mode.

FIG. 3 shows a flowchart of a method 300, which as an example of animplementation of the RRC variable HS_DSCH_RECEPTION_GENERAL accordingto the above description. The WTRU 110 begins checking conditions forthe variable HS_DSCH_RECEPTION_GENERAL (301), which comprises thefollowing checks. If the cell or state in which the WTRU hastransitioned to does not support HS-DSCH (302), then the variableHS_DSCH_RECEPTION_GENERAL is checked for TRUE (306). If the variable isTRUE, the variable is set to FALSE (307) and the HSDPA resources arereleased (308). If HS-DSCH reception is supported (302), and if the WTRU110 is not in one of the paging states (Cell_PCH/URA_PCH) (303), thenthe WTRU checks the SIB5/5bis for presence of the IE HS-DSCH commonsystem information (305). If this IE is not present, and the variableHS_DSCH_RECEPTION_GENERAL is TRUE (306), then the variableHS_DSCH_RECEPTION_GENERAL is set to FALSE (307) and HSDPA resources arereleased (308). If the WTRU 110 is in a paging state (Cell_PCH/URA_PCH)(303) and the IE HS-DSCH paging system information is not included inthe SIB5/5bis, then variable HS_DSCH_RECEPTION_GENERAL is checked forwhether it is set to TRUE (306). If TRUE, then variableHS_DSCH_RECEPTION_GENERAL is set to FALSE (307) and HSDPA resources arereleased (308).

HSDPA Variable Applicable to Paging Channel

In another embodiment, a new variable for Cell_PCH/URA_PCH isintroduced. The new variable HS_DSCH_RECEPTION_PCH_STATE is used toindicate if HS-DSCH reception is ongoing in Cell_PCH or URA_PCH. In thisembodiment, a variable for each state may exist, and the variables areused to evaluate and indicate if HS-DSCH reception is supported whenentering a new state.

The WTRU 110 evaluates and performs the actions associated with thefollowing HS_DSCH reception variables that correspond to the state theWTRU 110 is entering:

-   -   a. HS_DSCH_RECEPTION_OF_Cell_FACH_STATE;    -   b. HS_DSCH_RECEPTION_OF_CCCH_ENABLED is only evaluated when the        WTRU 110 moves or stays in Cell_FACH state;    -   c. HS_DSCH_RECEPTION_PCH_STATE is evaluated and actions are        performed when entering or staying in Cell_PCH state; or    -   d. HS_DSCH_RECEPTION is evaluated only when moving or staying or        reconfiguring in Cell_DCH.

The WTRU 110 has to evaluate these four variables when HS-DSCH receptioncriteria is not fulfilled and when it is fulfilled. The rationale behindthis procedure is that, when leaving a state or cell, the WTRU 110 maynot know in advance if HS-DSCH reception is supported in the new stateor cell. However, when entering the state or cell the WTRU 110 will knowthe results and capabilities of the state/cell, and it can also knowwhat it was previously supporting.

When evaluating the variables, if the requirements to enable HS-DSCHreception in the final state are not met, the actions associated to thevariable not being TRUE should be executed. These actions correspond toclearing of HSDPA resources. However, in order for the WTRU 110 to knowwhether HS-DSCH reception was ongoing prior to state transition or cellreselection, the WTRU 110 checks if any of the other HS_DSCH variablescorresponding to its own state and to the other states are set to TRUEat the time. This is an indication that the WTRU 110 had an ongoingHS-DSCH connection and thus it should clear the resources since itcannot support HS_DSCH reception.

In addition to clearing the HSDPA resources, the WTRU 110 also ensuresthat all other HS_DSCH reception state variables are set to FALSE.Further, the WTRU 110 performs the following:

-   -   stop any HS_SCCH reception procedures;    -   stop any HS-DSCH reception procedures;    -   clear the variable H_RNTI and remove any stored H-RNTI;    -   reset the MAC-ehs entity;    -   release all HARQ resources; and    -   clear any stored IEs HARQ info.

Optionally, to check if an HS-DSCH reception procedure was ongoing theWTRU 110 may also use the HS_DSCH_RECEPTION_GENERAL variable that setforth herein. When the HS-DSCH reception state variable being evaluatedis set to FALSE and the HS_DSCH_RECEPTION_GENERAL is set to TRUE, theactions associated to clearing the resources are cleared and thevariables are set to FALSE.

Modification of HS-DSCH Reception Variables.

The following are modifications to the existing HS-DSCH receptionvariables with respect to the paging channel states:

-   -   a. A new variable HS_DSCH_RECEPTION_PCH_STATE is monitored for        URA_PCH and CELL_PCH states;    -   b. For the case where HS_DSCH_RECEPTION_OF_CCCH_ENABLED and        HS_DSCH_RECEPTION_PCH_STATE is set to FALSE, and any of the four        variables indicate that HS-DSCH reception is ongoing, the        resources are cleared;    -   c. The WTRU 110 checks HS_DSCH_RECEPTION and        HS_DSCH_RECEPTION_OF_CELL_FACH_STATE if any of the four        variables are set to TRUE.        In the case where HS_DSCH_RECEPTION_GENERAL is used to indicate        if HS-DSCH reception is ongoing, the actions related to checking        if any of the four (4) HS-DSCH reception variables are set to        TRUE, are replaced by the action of only checking if        HS_DSCH_RECEPTION_GENERAL is set to TRUE.

With respect to the HS_DSCH reception variable for paging channels,variable HS_DSCH_RECEPTION_PCH_STATE is set to TRUE if HS-DSCH receptionin CELL_PCH or URA_PCH is ongoing. The variableHS_DSCH_RECEPTION_PCH_STATE is set to FALSE when the WTRU 110 isentering UTRA RRC connected mode when not otherwise stated in theprocedure, when the WTRU 110 is leaving UTRA RRC connected mode, andwhen the WTRU 110 is entering CELL_FACH and CELL_DCH.

Additional Modifications

Some additional modifications may be necessary if the WTRU 110 uses theHS-DSCH reception variables of other states as an indication of anongoing procedure.

Note that this modification may apply to other embodiments that alsorely on the other state HS-DCH reception variables for an indicationthat HS-DSCH reception is ongoing. In the case where theHS_DSCH_RECEPTION_GENERAL variable is used as an indication thesemodifications are not required.

The following modifications may be optionally implemented:

-   -   1. The WTRU 110 does not evaluate the actions related to        HS_DSCH_RECEPTION when moving out of Cell_DCH;    -   2. if any IEs related to HS-DSCH are stored in the WTRU 110        clear any stored IE “Downlink HS-PDSCH information”. The WTRU        110 does not set the HS_DSCH_RECEPTION_OF_CCCH_ENABLED.

The variable is set to FALSE only if the conditions to start performingHS-DSCH reception with a dedicated H-RNTI are successfully performed,otherwise it will be set to FALSE when the WTRU 110 fails to perform aHS-DSCH reception procedure.

Alternatively, the WTRU 110 ensures that the HS-DSCH reception variablesare set to FALSE when moving out of a state. For example, the variableHS_DSCH_RECEPTION_Cell_FACH_STATE is set to FALSE when moving out ofCell_FACH. However, this should also be done after the configuration ofthe other state is completed.

Clearing HSDPA Resources During Cell/State Transitions

In this embodiment the existing HS-DSCH reception variables are modifiedsuch that when transitioning between cells and states, the HS-DSCHreception procedures are stopped.

When moving out of Cell_DCH, the WTRU 110 clears the HSDPA resources ifthe WTRU 110 is moving to a state that HS-DSCH reception is notsupported. More specifically, the HS_DSCH_RECEPTION variable is modifiedsuch that the WTRU 110 can check if HS-DSCH reception will be supportedin the other states by the WTRU 110 and the network. This may be done bychecking one or a combination of the following conditions:

-   -   3. WTRU 110 does not support HS-DSCH reception;    -   4. Alternatively, if additional WTRU 110 capabilities are added        (such as WTRU 110 supports HS-DSCH reception only in Cell_FACH        and WTRU 110 supports HS-DSCH reception in Cell_PCH and in        Cell_FACH) the WTRU 110 may check for these specific conditions        in the respective states;    -   5. IE “HS-DSCH common system information” is not included in the        SIB5/5bis;    -   6. For Cell_PCH and URA_PCH, the IE “HS-DSCH paging system        information” is not included in SIB5/5bis.        If one of the above conditions is TRUE, the WTRU 110 clears all        HSDPA resources. This will guarantee that moving from Cell_DCH        to any other non-HSDPA state will free all resources and stop        HS-DSCH reception procedures.

In addition, when moving from Cell_PCH or URA_PCH state to Cell_FACHstate due to cell re-selection, the WTRU 110 requires an indicationwhether HS-DSCH reception procedure is ongoing. This is required, if theWTRU 110 transitions to another state or performs cell reselection to acell that does not support HS-DSCH reception. The WTRU 110 should beable to detect that HS-DSCH reception is ongoing and that HSDPAresources are to be cleared. This may be done by the addition of a newHS_DSCH_RECEPTION_PCH_STATE variable that is set to TRUE when the WTRU110 meets the conditions to start HS-DSCH reception. The variable willbe set to FALSE when HS-DSCH reception is stopped.

When performing state transitions and cell re-selections to states suchas Cell_FACH, URA_PCH, and Cell_PCH, the conditions to perform HS-DSCHreceptions are checked. If they are not met, in addition to performingS-CCPCH reception, the WTRU 110 also performs one of the following:

-   -   7. Evaluate the variable HS_DSCH_RECEPTION_OF_Cell_FACH_STATE        and perform the corresponding actions: if the requirements are        not met and if HS-DSCH reception is ongoing, the HSDPA resources        are to be cleared;    -   8. In order to be able to assess if there are any ongoing        HS-DSCH procedures in the current state or in the other states,        additional checks should be performed. For example, the WTRU 110        should also check if the HS_DSCH_RECEPTION_OF_CCCH_ENABLED or        HS_DSCH_RECEPTION_PCH_STATE or HS_DSCH_RECEPTION_Cell_FACH_STATE        is set to TRUE. If any of the variables are set to TRUE then the        WTRU 110 clears the resources and sets all the variables to        FALSE;    -   9. The WTRU 110 does not need to check if        HS_DSCH_RECEPTION_OF_CCCH_ENABLED is set to FALSE, when        evaluating the need to clear HS-DSCH resources.    -   10. Evaluate the variable HS_DSCH_RECEPTION_OF_CCCH_ENABLED.        Additional actions related to the case where the conditions        required to setup HS-DSCH reception are not fulfilled.

The WTRU 110 should be capable of checking if any of the HS-DSCHreception variables are set to TRUE (i.e. indicating that HS-DSCHreception is ongoing).

If any variables are set to TRUE, the WTRU 110 should clear allresources and set all the variables to FALSE, evaluate a variable andperform actions according to one of the procedures specified in any ofthe previous embodiment or as in the specification.

Lastly, the WTRU 110 must ensure that the variables are set to FALSEwhen stopping HS-DSCH reception in one state (i.e. when changing fromcommon to dedicated H-RNTI, when changing states, and when changingcells).

Releasing Resources when HS-DSCH Reception Conditions not Met

In another embodiment, the WTRU 110 always releases the resources whenthe conditions to perform HS-DSCH reception are checked and notfulfilled. Optionally, the WTRU 110 could use a MAC-ehs state indication(e.g. HARQ configured) to determine whether or not the WTRU 110 has anongoing HSDPA setup.

The proper behaviour when stopping HS-DSCH operation should be specifiedwherever the following conditions are checked:

-   -   for TDD; or    -   for FDD, if the WTRU 110 does not support HS-DSCH reception; or    -   if the IE “HS-DSCH common system information” is not included in        System Information Block type 5 or System Information Block type        5bis; or    -   for TDD; or    -   for FDD, if the WTRU 110 does not support HS-DSCH reception; or    -   if the IE “HS-DSCH paging system information” is not included.        These conditions are checked in various places, including the        following:    -   System Information Block 5 and 5bis    -   System Information Block 6    -   Reception of a Setup/Reconfiguration/Release message by the WTRU        110    -   Cell Update, initiation    -   Reception of Cell Update Confirm message by the WTRU 110    -   Timer T302 expiry or cell reselection    -   Initiation (RRC CONNECTION REQUEST)    -   Reception of an RRC CONNECTION SETUP        When one of these above conditions is satisfied, the proper WTRU        110 behaviour is as follows:    -   stop any HS-SCCH reception procedures;    -   stop any HS-DSCH reception procedures;    -   clear the variable H_RNTI and remove any stored H-RNTI;    -   reset the MAC-ehs entities;    -   release all HARQ resources;    -   clear any stored IEs HARQ info.

Alternatively, the following exemplary instructions for the WTRU 110clear the HSDPA resources only if HS-DSCH reception is ongoing bychecking if any of the state variables are set to TRUE.

Release of HSDPA Resources

If one of the variables HS_DSCH_RECEPTION_Cell_FACH_STATE ENABLED orHS_DSCH_RECEPTION or HS_DSCH_RECEPTION_OF_CCCH_ENABLED orHS_DSCH_RECEPTION_PCH_STATE is set to TRUE, the WTRU 110 shall:

-   -   11. set the variables HS_DSCH_RECEPTION_Cell_FACH_STATE,        HS_DSCH_RECEPTION, HS_DSCH_RECEPTION_OF_CCCH_ENABLED, and        HS_DSCH_RECEPTION_PCH_STATE to FALSE;    -   12. stop any HS_SCCH reception procedures;    -   13. stop any HS-DSCH reception procedures;    -   14. clear the variable H_RNTI and remove any stored H-RNTI;    -   15. reset the MAC-ehs entity;    -   16. release all HARQ resources; and    -   17. clear any stored IEs HARQ info.

Although features and elements are described above in particularcombinations, each feature or element can be used alone without theother features and elements or in various combinations with or withoutother features and elements. The methods or flow charts provided hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable storage medium for execution by ageneral purpose computer or a processor. Examples of computer-readablestorage mediums include a read only memory (ROM), a random access memory(RAM), a register, cache memory, semiconductor memory devices, magneticmedia such as internal hard disks and removable disks, magneto-opticalmedia, and optical media such as CD-ROM disks, and digital versatiledisks (DVDs).

Suitable processors include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs) circuits, any other type of integratedcircuit (IC), and/or a state machine.

A processor in association with software may be used to implement aradio frequency transceiver for use in a wireless transmit receive unit(WTRU), user equipment (UE), terminal, base station, radio networkcontroller (RNC), or any host computer. The WTRU may be used inconjunction with modules, implemented in hardware and/or software, suchas a camera, a video camera module, a videophone, a speakerphone, avibration device, a speaker, a microphone, a television transceiver, ahands free headset, a keyboard, a Bluetooth® module, a frequencymodulated (FM) radio unit, a liquid crystal display (LCD) display unit,an organic light-emitting diode (OLED) display unit, a digital musicplayer, a media player, a video game player module, an Internet browser,and/or any wireless local area network (WLAN) or Ultra Wide Band (UWB)module.

What is claimed is:
 1. A method implemented by a wireless transmitreceive unit (WTRU), the method comprising: receiving, by the WTRU,broadcast information; checking, using the broadcast information, that acell serving the WTRU supports high speed reception in a paging state oncondition that the WTRU has transitioned to the paging state; setting ahigh speed reception variable associated with at least the paging stateto a first value on condition that the WTRU or the cell serving the WTRUdoes not support the high speed reception; setting the high speedreception variable associated with at least the paging state to a secondvalue on condition that the WTRU and the cell serving the WTRU supportthe high speed reception; and releasing high speed resources oncondition that the high speed reception variable is set to the firstvalue.
 2. The method of claim 1, further comprising determining whetherthe WTRU has transitioned to any of: a Cell_PCH state or a URA_PCHstate, as the paging state.
 3. The method of claim 1, wherein thechecking that the paging state supports the high speed receptionincludes decoding an Information Element (IE) in the broadcastinformation of a broadcast from the cell to determine a high speedreception status.
 4. The method of claim 3, wherein the decoding of theIE in the broadcast information includes decoding a High Speed-DownlinkShared Channel (HS-DSCH) paging system information IE.
 5. The method ofclaim 1, wherein the releasing of the high speed resources is furtherconditioned on the high speed resources being previously set.
 6. Themethod of claim 1, further comprising: receiving a communication over aHigh Speed-Downlink Shared Channel (HS-DSCH) on condition that the cellserving the WTRU supports the high speed reception; receiving thecommunication over a non-high speed channel on condition that the cellserving the WTRU does not support the high speed reception; and decodingthe received communication.
 7. The method of claim 1, furthercomprising: on condition that the WTRU is in or transitions into anon-paging state, setting any of: a HS_DSCH_RECEPTION_OF_CCCH_ENABLEDvariable or a HS_DSCH_RECEPTION_Cell_FACH_STATE variable, theHS_DSCH_RECEPTION_OF_CCCH_ENABLED variable and theHS_DSCH_RECEPTION_Cell_FACH_STATE variable being different variablesthan the high speed reception variable.
 8. A wireless transmit receiveunit (WTRU) configured to manage a transition to a paging state,comprising: a transmit/receive unit configured to receive broadcastinformation; a processor configured to: check, using the broadcastinformation, that a cell serving the WTRU supports high speed receptionin the paging state on condition that the WTRU has transitioned to thepaging state; set a high speed reception variable associated with atleast the paging state to a first value on condition that the WTRU orthe cell serving the WTRU does not support the high speed reception;setting the high speed reception variable associated with at least thepaging state to a second value on condition that the WTRU and the cellserving the WTRU support the high speed reception; and release highspeed resources on condition that the high speed reception variable isset to the first value.
 9. The WTRU of claim 8, wherein the processor isconfigured to determine whether the WTRU has transitioned to any of: aCell_PCH state or a URA_PCH state, as the paging state.
 10. The WTRU ofclaim 8, wherein the processor is configured to decode an InformationElement (IE) in the broadcast information of a broadcast from the cellto determine a high speed reception status.
 11. The WTRU of claim 10,wherein the processor is configured to decode a High Speed-DownlinkShared Channel (HS-DSCH) paging system information IE.
 12. The WTRU ofclaim 8, wherein the processor is configured to release the high speedresources further conditioned on the high speed resources beingpreviously set.
 13. The WTRU of claim 8, wherein: the transmit/receiveunit is configured to: receive a communication over a HighSpeed-Downlink Shared Channel (HS-DSCH) on condition that the cellserving the WTRU supports the high speed reception, and receive thecommunication over a non-high speed channel on condition that the cellserving the WTRU does not support the high speed reception; and theprocessor is configured to decode the received communication.
 14. TheWTRU of claim 8, wherein the processor is configured to: set any of: aHS_DSCH_RECEPTION_OF_CCCH_ENABLED variable or aHS_DSCH_RECEPTION_Cell_FACH_STATE variable, on condition that the WTRUis in or transitions into a non-paging state, theHS_DSCH_RECEPTION_OF_CCCH_ENABLED variable and theHS_DSCH_RECEPTION_Cell_FACH_STATE variable being different variablesthan the high speed reception variable.